Update sbt.project with sbt 1.5.0 API

```
/home/runner/work/lagom-starter-minimal/lagom-starter-minimal/build.sbt:2: warning: method in in trait ScopingSetting is deprecated (since 1.5.0): `in` is deprecated; migrate to slash syntax - https://www.scala-sbt.org/1.x/docs/Migrating-from-sbt-013x.html#slash
organization in ThisBuild := "com.tiarebalbi"
``` 